Scientists find link on SIDS

Scientists have new evidence that the brain chemical best known for regulating mood also plays a role in the mystifying killer of seemingly healthy babies – sudden infant death syndrome.

Autopsied brain tissue from SIDS babies first raised suspicion that an imbalance in serotonin might be behind what once was called crib death.

But specialists couldn't figure out how that defect could kill. Now, researchers in Italy have engineered mice born with serotonin that goes haywire – and found the brain abnormality is enough to spur sudden death.

Moreover, the work suggests it might one day be possible to test newborns for risk of SIDS.

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For now, even an animal experiment can offer a message for devastated families:

“It should provide them with some sense of comfort that there was nothing they could have done to prevent it,” said Dr. Marian Willinger, a SIDS specialist at the National Institute of Child Health and Human Development, who wasn't part of the study.

The work was published in today's edition of the journal Science.

SIDS is the sudden death of an otherwise healthy infant – anywhere between the ages of 1 month and 1 year – that can't be attributed to any other cause. It kills more than 2,000 infants in the U.S. each year.

Babies should always be placed to sleep on their backs, as the risk of SIDS increases greatly when babies sleep on their stomachs. And parents are urged not to allow anyone to smoke around their babies, or to let their babies get too warm while sleeping.

But beyond those risk factors, doctors have little advice.

In 2006, Dr. Hannah Kinney of Children's Hospital Boston compared brain tissue from 31 SIDS babies and 10 infants who died of other causes. The SIDS babies had abnormalities in their brain stem that led to imbalances in serotonin, a neurotransmitter or chemical that helps brain cells communicate.

Low serotonin famously plays a role in depression. Less-known to laymen is that it also helps regulate some of the body's most basic functions – breathing, heart rate, body temperature.

Dr. Cornelius Gross and colleagues at the European Molecular Biology Laboratory in Italy were studying how the serotonin system turns itself on and off when they stumbled onto the SIDS connection.

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